Method of and apparatus for hardening steel ribbon



(N 0 Model.)

--J.LOGA N. METHOD OP AND APPARATUS FOR HARDENING STEEL RIBBON.

No. 297,610. Patented Apr. 29,1884.

I V E in I J fin 113x71 5y /fttjs 555E. WQ hm N Pzrzns. Photo-lithography. Washington. a. Q

,UN'ITED STATES PATENT GFFICE.

JOHN LOGAN, OF WALTHAM, MASSACHUSETTS.

METHOD OF AND AP PARATUS FOR HARDENING STEEL RIBBON.

SPECIFICATION forming part of Letters Patent No. 297,610, dated April 29, 1884-.

Application filed December 13, 1883. (N0 model.) i o I T0 at whom it may concern:

Be it known that I, J OHN LOGAN, of Waltham, county of Middlesex, State of Massachusetts, have invented an Improvement in Methods of and Apparatus for Hardening Steel -Ribbon, of which the following description,

in connection with the accompanying drawngs, 1s a specification, like letters on the drawlngs representing like parts.

My invention relates to the manufacture of steel springs, such as employed, for the mainsprings of watches and clock-work or for other purposes. In the process of manufacture of spr1ng-steel as commonly practiced, the soft steel, made into a ribbon or thin band of the proper shape, is drawn progressively through a furnacemuffle or a bath of highly-heated molten metal to give the steel ribbon a red heat, and upon issuing from the furnace or bath the said metal is suddenly cooled, making it very hard and brittle, after which the ribbon, thus hardened, is tempered to give it the requisite elasticity. When a thin ribbon is thus drawn progressively through a furnace or highly-heated bath, it quickly assumes the temperature of the material surrounding it, and is quicklyaffected by variations in temperature; and when it passes through a muffle or heated chamber not containing a liquid its different parts are apt to be heated unequally, and the product is not uniform in character; and, furthermore, it requires great skill and care on the part of the operator to obtain a satisfactory result. In order to produce the best spring-steel, the ribbon should be heated to a red-heat gradually and uniformly throughout its entire length, and it is desirable to protect its surface from the action of air or other gases which tend to oxidize or chemically combine with it when at a high temperature, thus greatly diminishing the subsequent labor of polishing and finishing.

The present invention has for its object to insure the gradual and absolutely uniform heating of the ribbon; and it consists, mainly, in providing an inclosing-case in which the said ribbon, when wound into a tight compact coil, is inclosed, the said case being heated, together with the inclosed ribbon, to the desired temperature, and by its great mass or body causing the rise in temperature of the I inclosed ribbon to be gradual, and preventing any sudden changes in temperature, while the inclosed ribbon, being wound in a tight coil, occupiesbut smallspace, and is uniformly affected in all parts. When the case, with the inclosed ribbon, has been heated to aproper temperature, the ribbon is unwound from the said case and drawn through the cooling-bath, or is otherwise suddenly cooled. The case for containing the ribbon may be of various forms of construction, the one herein shown being made in two parts to receive the coil of ribbon between them, and being provided with a nose or passage, through which the ribbon is drawn, the coil of ribbon turning on asuitable pivot or center in the case in unwinding.

Apparatus for hardening wire or ribbon has been made in which the said ribbon is drawn progressively through amuffle or chamher from which the air is excluded, as far as possible, by means of packing, and the ribbon is drawn directly from the said muffle into the cooling-bath, which is placed as near to the muffle as possible, so that the ribbon isbut slightly exposed to the air in its passage from the muffle to the bath. The ribbon has also been coiled in boxes, and hardened and tempered while held therein, so that the ribbon, when removed, retains the shape it had when in the box, and this method cannot be followed when the finished ribbon is to have any other shape than that of a closewound coil.

Figure 1 is a sectional view of an apparatus for hardening steel ribbon preparatoryto tempering in accordance with this invention; Fig. 2, a side elevation of the ribbon-containing case and ribbon coiled thereon, the cover of the case being removed; and Fig. 3, a section of the said case with its cover on the line 00, Fig. 2.

The furnace a, muffle b, in which the rib bon is to be heated, and the bath 0, through which the heated ribbon e is drawn by means of the reel or winding-drum d, may be of any suitable or usual construction and arrangement.

The ribbon e, to be hardened, instead of being drawn progressively through the furnace or muffle, is coiled tightly, as shown at c, Fig. 2, and inclosed in a heating-case, f, composed of iron or other metal not fusible at the temperaturc to which the inelosed steel is to be I treatment for making the finished springs,

heated. As herein shown, the. said case consists of a main or body portion, g, having a flange, 71., of a depth about equal to the width of the ribbon to be hardened, provided with a central pin or stem, 5, around which the coiled ribbon c is placed, and upon which the said coil revolves as a center when it is unwound. The said body is provided with a trough-like nose, 7., through which the ribbon passes when being unwound, it protecting the ribbon and keeping 'it heated until it enters tongs to draw it out, and the end of the nose is plugged up tightly with asbestus or equivalent material, as shown at 7 thus wholly preventing the access of air to the ribbon in the process of heating. The case is preferably provided with a projection, r, to serve as ahandle to enable it to be moved to the proper position in the mufilc to draw out the ribbon, as shown in Fig. 1; or, if desired, the case may be wholly removed from the furnace before the ribbon is drawn out from it, the case being of sufficient size to remain sufliciently heated until the ribbon is all drawn out from it. By thus protecting the ribbon from the air while it is being heated, its surface will be comparatively unchanged, so that it may be highly finished or polished before being hardened, and will subsequently require but very little while by the usual process of progressively heating the ribbon it burns or oxidizes more or less, so that it requires to have its surface subsequently polished at a large expenditure of labor, in order to give it the requisite finish. The spring-ribbon produced by my improved process is much tougher and less liable to be broken in use than springs made by the processes heretofore employed.

I claim- 1. That improvement in the art or. method of hardening steel ribbon for springs which consists in coiling the ribbon and inclosing the coiled ribbon in a case or body of metal, heating it therein, and uncoiling or unwind-- ing the heated ribbon and cooling the same as it is unwound, substantially as described. 5

2. The furnace, combined with a case inclosing the coiled ribbon to be hardened, and protecting the said ribbon from the air or gases in the furnace, and means to cool the said ribbon as it is unwound from the case, substantially as described.

3. The ease having a flanged main or body portion and cover, combined with a central pivot for the coil of ribbon, the said case having a nose for guiding and protecting the ribbon as it is unwound from the interior of the case.

I11 testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JOHN LOGAN.

\Vitnesses:

Jos. I. LIVERMORE, B. J. Novas. 

